Positively reinforce student contributions. You can emphasize the value of student responses by restating their comments, writing their ideas on the board, and/or making connections between their comments and the discussion at large. Also be sure to maintain eye contact and use non-verbal gestures such as smiling and head nodding to indicate your attention and interest in students' responses.
Use a "token system" to encourage discussion. Distribute three pennies or poker chips to each student at the outset of the discussion. Each time a student speaks, a penny/chip is turned in to the facilitator. The goal is for students to spend all their pennies/chips by the end of the session. This system can be useful for limiting students who dominate the discussion and encouraging quiet students to contribute.
Limit your own involvement. Avoid the temptation to talk too much and/or respond to every student's contribution. After you ask students a question, count to at least five in your head before answering it yourself. When you ask students a question, if you really want them to think and be able to give an answer, be willing to wait for it. Try to encourage students to develop their own ideas and to respond to one another (that is, peer interaction). You might also sit someplace other than the "head" of the table.
Balance students' voices during the discussion. Here are some strategies for dealing with problem group members who can affect the level of student participation:
Discourage students who monopolize the discussion by implementing a structured activity that requires each group member to be involved, avoiding eye contact with him/her, assigning a specific role to the dominant student that limits participation (e.g., discussion recorder), or implementing time limits on individual contributions.
Draw quiet students into the discussion by posing non-threatening questions that don't require a detailed or correct response, assigning a small specific task to the student (e.g., obtaining information for next class), sitting next to him/her, or positively reinforcing contributions he/she does make.
Clarify confusing student contributions by asking the student to rephrase/explain the comment, paraphrasing the comment if you can interpret it, asking the student probing questions, or encouraging him/her to use concrete examples and metaphors.